Effects of host plant leaf damage on cabbage looper moth attraction and oviposition

Mated female Trichoplusia ni (Hubner) moths, when presented a choice of either undamaged cotton plants, Gossypium hirsutum L., or damaged plants (cut leaves or feeding T. ni larvae) in a flight tunnel, were most often attracted first to the damaged plants. However, these same moths oviposited primarily on the undamaged plants. In a similar test with cabbage plants, Brassica oleracea L., the presence of conspecific larvae decreased both attraction and oviposition. Cuts to cabbage leaves had no significant effect on attraction or oviposition. When presented one plant at a time, percentages of cabbage looper moths attracted were not affected by the presence of larvae on either cabbage or cotton plants, or by cuts to cabbage plant leaves. Percentages of moths attracted were, however, higher using cotton plants with cut leaves. The results suggest an important role for damage induced plant volatiles in host location as well as host acceptance by T. ni.